FIELD OF THE INVENTION
The present invention relates to a fiber optical device for measuring physical magnitudes such as force, elongation, pressure, acceleration, temperature, etc., and comprises a transducer unit and an electronics unit, in which the quantity to be measured in supplied to the transducer unit to affect the resonance frequency of an oscillating body included in the transducer unit by changing the dimensions, mass, density, modulus of elasticity and/or mechanical stress of the body. The properties of the body oscillation, such as frequency, phase position and/or amplitude, are used as a value of the quantity to be measured.